Support cushion



FIG. 1 is a top, front and left side perspective view of a support cushion showing my new design, the undisclosed right side being a mirror image of that shown;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof; and

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a support cushion, as shown and described. 